Help, Fin Rot or Fin loss supected

[Williamg]

Well some negative progress. My betta (I really need a name for him) managed to put some holes and blow part of his fin. I haven't a clue how he managed to do this, his tank is empty. I removed the dangerous fake plant, and nothing else in his tank is sharp or pointing. Maybe the lack of hiding places is stressing him out and making him flare more, but there is nothing much I can do until the bulbs I have planted in his tank get bigger. Right now they just started to grow, and are about 2 to 3 cm long. On the brightside, he is recovering from the fin rot. Any advice?
Williamg

[derpmeister]

Is the current from the filter strong? Sometimes it can create tears and holes in betta's tails, especially if they're big. This is a big problem with halfmoon bettas. Also, new fin growth is super delicate and easily broken. If this is your problem, you could create a baffle with a plastic bottle or a sponge in front of the filter outflow.

[Williamg]

The filter is a whisper 3I, and I have never had any issues with it at all. The suction isn't great, and the current ends after in hits the front of the tank. And derpmeister, none of the new growth as been damaged at all. It was a completely different area of the tail that had never had any damage on it before. Its really odd.
Williamg